Polyamides stabilised against degradation by light

ABSTRACT

POLYAMIDES, STABILIZED AGAINST DEGRADATION BY LIGHT, CONTAINING A COMBINATION OF MANGANESE COMPOUNDS AND PHOSPHOROUS COMPOUNDS OF THE GENERAL FORMULA   R1-P(-R2)-R3 OR O=P(-R1)(-R2)-R3   WHEREIN R1, R2, AND R3, WHICH MAY BE DIFFERENT OR NOT, REPRESENT ALKYL, CYCLOALKYL, ARALKYL, ARYL, ALKOXY, CYCLOALKOXY, ARALKOXY OR ARYLOXY RADICALS.

United States Patent Int. Cl. cos 51/62 US. Cl. 260-4575 Claims ABSTRACT OF THE DISCLOSURE Polyamides, stabilized against degradation by light, containing a combination of manganese compounds and phosphorous compounds of the general formula wherein R R and R which may be different or not, represent alkyl, cycloalkyl, aralkyl, aryl, alkoxy, cycloalkoxy, aralkoxy or aryloxy radicals.

The present invention relates to polyamides which are stabilised against degradation by light containing a combination of manganese compounds and certain phosphorous compounds as stabilisers and to a process for their preparation.

Shaped articles made of polyamides which have been made by polymerisation of diamines and dicarboxylic acids or of aminocarboxylic acids or their lactams, for example, filaments, bristles or foils, are damaged by the action of light. The light has the effect of reducing the relative viscosity of the polyamide and the mechanical strength and stretching properties are impaired. This sensitivity to light is especialy high in polyamides which contain inorganic pigments such as TiO as matting agents or dyes.

.Numerous stabilisers have therefore been proposed for improving the resistance of polyamides to light. Manganese compounds such as the oxalate, hypophosphite, borate, silicate, acetate, phosphate, polyphosphate complexes, and adipate are reported to be especially effective light stabilisers for polyamides. The manganese compounds previously used have the disadvantage that they decompose during polymerisation to form manganese dioxide, which causes discolouration of the polyamide. Their electrolytic character may also cause agglomeration and precipitation of the pigment that is finely dispersed in the polyamideforming starting material, this agglomeration and precipitation interferes with the Working up of the polyamide to form filaments. The manganese compounds may also precipitate from the polyamide melt in the course of the polymerisation in the form of moderately large crystals which cause filter blockages during spinning and other difficulties.

It is an object of this invention to provide polyamides, stabilised against degradation by light, which do not show the disadvantages discussed above.

This object is accomplished by a polyamide, stabilised against degradation by light, containing, as stabiliser, a combination of (a) a manganese compound in such a quantity that 0.0001 to 0.01% by weight, based on the polyamide, of a manganese are present and (b) 0.0001 to 0.1% by weight, based on the polyamide,

of a phosphorous compound of the general formula wherein R R and R which may be different or not, represent substituted or unsubstituted alkyl, cycloalkyl, aralkyl, aryl, alkoxy, cycloalkoxy, aralkoxy or aryloxy radicals, the atomic ratio of P and Mn in said combination being from 0.5 to 10.

It is a further object of this invention to provide a process for the production of polyamides, stabilised against degradation by light, which comprises adding to the polyamides or to the polyamides forming starting mixture a combination of (a) a manganese compound and (b) a phosphorous compound of the general formula wherein R R and R which may be different or not, represent substituted or unsubstituted alkyl, cycloalkyl, aralkyl, aryl, alkoxy, cycloalkoxy, aralkoxy or aryloxy radicals.

Examples of phosphorous compounds that are suitable according to the invention are triphenylphosphine, tritolylphosphine, phenyldimethylphosphine, tributylphosphine, tricyclohexylphosphine, triisopropylphosphine, tris ,6 cyanoethylphosphine, triphenylphosphite, trisnonylphenylphosphite, tridecylphosphite, didecylphenylphosphite, tris-fi-chloroethylphosphite, triphenylphosphine oxide, tributylphosphine oxide and tricyclohexylphosphine oxide.

The manganese compounds used are preferably manganese-II salts of inorganic and organic acids, for example, MnSO manganese acetate, manganese oxalate and manganese stearate, the manganese-II-halides, MnCl- MnBr and Mnl being preferred. The manganese compounds are advantageously used in quantities such that the polyamide contains 0.0001 to 0.01% by weight, preferably 0.0002 to 0.005% by weight, based on the polyamide, of manganese.

The phosphorous compounds are advantageously added in an amount of 0.0001 to 0.1% by weight, preferably 0.0005 to 0.01% by weight, based on the polyamide, and the atomic ratio of PzMn may be between 0.5 and 10 and is preferably between 1 and 5.

The combinations of manganese compounds and phosphorous compounds according to the invention are either mixtures of the components or stable, crystalline or liquid, addition compounds of the formula wherein X represents a halogen atom, m is 1 or 2, and R R and R represent the same or different substituted or unsubstituted alkyl, cycloalkyl, aralkyl, aryl, alkoxy, cycloalkoxy, aralkoxy or 'aryloxy radicals.

3 4 The following are examples of such addition comabout 3 mm. in diameter and 0.01 mm. in thickness is cut pounds: out by means of a suitable cutting device, for example a MnBr 2[(c6H5)3P=O] microtome. These microtome sections are then inspected with a measuring microscope with 100 times magnification 2' s 5)a under an oblique direct light and the pigment particles or M I C H 3 agglomerates which have a maximum size of to n 2 6 5)3 10 to 1,, 15 to p, etc., respectively are counted. The 2' s s)3 results are summarised in Table l. The polymers are spun MnC12.2[(C6H5)3p] into silk with 90/25 don, the melt being filtered through 10 a wire gauze of 10 mesh before entering into the spin- MnC12'[(C1H21 O)3P] ning dyes. In the case of samples 9, 10 and 11, the pres- M I -2[(C H P=()] sure in front of the wire filter gauze rapidly rises during spinning, so that satisfactory spinning becomes no longer Mnclz [(C1CH2 CH2 O)3P] possible. When the filter is taken apart, it is found to be These addition compounds can easily be prepared by 15 badly blocked with a material which according to analymethods described in the literature, for example, by retical investigation consists of 10 to Ti0 and 5 to acting manganese-II-halides with the corresponding phos- 30% Mn in the form of an inorganic compound. phorous compounds (J. Chem. Soc., 1961, 3735; Chem. In the case of Samples 1 to 8, the pressure in front of Abs. 56, 13783 C) and are readily soluble in organic solthe wire filter gauze remains practically constant during vents such as butanol, methylene chloride, dimethylform- 20 spinning and no disturbances occur in spinning. When the amide, toluene or acetone as well as in monomeric lacfilter is removed, it is found to be on the whole clean. tams, for example, caprolactam. To determine the stability to light, the filaments are irra- The stabiliser combination may be added to the polydiated with a 1,500 watt xenon arc lamp for 200 hours; amide-forming starting mixture before polymerisation or the loss in mechanical strength resulting from these irrapolycondensation, and the polymerisation may then be 5 diations is shown in Table 2.

TABLE I Mn content in finished Pigment distribution Serial product in Number Manganese compound Grams p.p.m. Colour of the polyamtde 5-10 10-15 15-20;: 20

1 Mncl-2 trlphenylphosphine oxide 31.0 Pure white 2 MnBIz-Z tripheuylphosphine oxide. 35. 0 d0 MnI2-2 triphenylphosphine 37. 0

MnClz-Z tributylphosphine oxide. 29. 6 6.-.. MnGlz-2 trideeylphosphite 32. 6 6 {MnClz-4Hz0 9. 0

Trlphenylphosphine oxide" 20. 0 7 Mn 12-4112 9.0 8-.-- Mn acetate 41320.. 11. 1

l\lnSO4-I-IzO 7. 7 10 Mn(HgPO4)2-5H2O 15. 4 11 Mn(HzPOz)2-H2O 9. 2

carried out in known manner either continuously or TABLE 2 intermittently. Les of m U Alternatively, the stabilisers, either separately or tovalu s in e reiiiit gether, or if deslred 1n the form of a concentrate 1n the 15 a polyamide, may be mixed with the polyamide melt during f f or after polymerisation or polycondensation, using known strength tearing mixing apparatus such as, extruders, kneaders, or stirrers.

Polyarnides are here understood to mean compounds 27 33 which can be prepared by polymerisation of lactams or 5f, fig by polycondensation of aminocarboxylic acids or of di- 2% gig amines and dicarboxylic acids. 28 39 In addition to the stabilisers, the polyamides may also contain the usual additives such as pigments, dyes, heat 36 50 stabilisers, optical brightening agents, crystallisation promoters etc.

Polyamides which have been stabilised in this way, especially against degradation by light, are eminently suitable for the production of filaments, for example, monofilament or multifilament silk, fibres or foils.

The following example 1s to further illustrate the mven- Sisting of Sulfate acetate, Oxalate, Stearate, chloride,

Wlthout hmmng bromide and iodide salts in such a quantity that EXAMPLE 0.0001 to 0.01% by weight, based on the polyamide,

of manganese is present and (b) 0.0001 to 0.1% by weight, based on the polyamide, of a phosphorous compound of the general formula What we claim is:

1. A polyamide, stabilized against degradation by light, containing, as stabilizer, a combination of (a) a manganese II salt selected from the group con- 110 kg. of caprolactam are polycondensed in the usual 35 manner in a pressure autoclave at 260 C. with the addition of 2 kg. of water, 0.3 kg. of TiO (anatase modification) in the form of an aqueous dispersion, 0.2 kg. of

acetic acid as chain breaking reagent and various man- P R2 0=PR1 ganese compounds (as given in Table I). The polyamide I ia I ta melt is then spun into a filament of about 3 mm. diamwherein R R and R which may be different or not, eter, granulat d, freed frOm mOIIOm iC C itu by are substituted or unsubstituted alkyl, cycloalkyl, aralkyl, boiling with water, and dried. The finished product is ary], alkoxy, cycloalkoxy, aralkoxy or aryloxy radicals; investigated for pigment distribution as follows: the atomic ratio of P and Mn in said combination being From 10 granulates picked out at random, a disc of from 0.5 to 10.

2. The stabilized polyamide of claim 1 wherein the manganese II salt is a manganese H halide.

3. The stabilized polyamide of claim 1 wherein the phosphorous compound is triphenylphosphine oxide.

4. The stabilized polyamide of claim 1 wherein the phosphorous compound is triphenyl phosphine.

5. A polyamide, stabilised against degradation by light, containing, as stabiliser, an addition compound of the general formula wherein X represents a halogen atom, m is 1 or 2, and R R and R which [may be difierent or not, represent substituted or unsubstituted alkyl, cycloalkyl, aralkyl, aryl, alkoxy, cycloalkoxy, aralkoxy or aryloxy radicals, said addition compound being present in such an amount that 0.0001 to 0.01% by weight, based on the polyamide,

of manganese are present.

References Cited UNITED STATES PATENTS DONALD E. CZAJA, Primary Examiner V. P. HOKE, Assistant Examiner U.S. Cl. X.R. 26037, 45.7, 45.9 

